# There are 5 miles to 8 km. How many km in 80 miles?

#### Risposta:

80 " miles" = 128 km

#### Spiegazione:

Write a direct proportion to compare miles to Km.

5/8 = 80/x" "(larr " miles")/(larr" km")

You could decide what 5 was multiplied by to give 80 and do the same to the 8.

5/8xx 16/16 = 80/128" "(larr " miles")/(larr" km")

Or Cross multiply to get:

5x = 8xx80

x =(8xx80)/5

x= 128 km

OR Find a conversion factor:

5 " miles " = 8 km

1 " mile " = 8/5 km

80 " miles " = 80 xx8/5 = 128 km